The present invention relates in general to meter reading, and, in particular, remotely reading groups of meters using a unidirectional communication system and protocol.
Utility companies are taking advantage of modem technology to reduce costs and increase efficiency in meter reading applications using wireless technology to remotely gather information from large groups of meters. Traditionally, utility meters, such as electric, water and natural gas, were manually read by utility workers visiting each meter location. Current technology allows meters to be remotely accessed from a central location through wire or wireless communication links. To further increase ease of reading and meter installation, these meters are battery powered and operate to gather parameter measurements for the respective types of meters, and various other information, and then communicate this information to a remotely situated meter reading device. Typically, large numbers of meters may be installed and configured to communicate wirelessly with a centralized remote meter reading device.
In order to keep maintenance low and operating efficiency high, it is desirable to have meters which can operate for an extended period of time without requiring maintenance, battery replacement and the like. Maintenance requirements are generally reduced by increasing battery capacity and reducing power consumption. As a result, the meters generally cycle between low-power sleep modes, to conserve energy, and full-power awake modes, when any combination of meter reading, information gathering, information processing and data transmission may occur. In order to further decrease meter cost and prolong battery life, these meters may be configured to only transmit data to the meter reading device since receiving data would result in a significant, additional toll on battery life.
In operation, the meters periodically awake from the sleep mode to gather information, such as meter parameter readings, and to check meter status. When the meter is awake, the parameter readings and meter status information may be wirelessly sent to the meter reading device and relayed on to a network or utility for processing the information.
In these applications, all of the meters located within range of the meter reading device must periodically transmit information to the meter reading device. As the number of meters increases, the likelihood of multiple meters transmitting information to the meter reading device at the same time increases. Furthermore, the frequencies at which these meters operate may likely be the same as other non-metering devices. The preferred bands are typically relatively narrow and made accessible to many different applications and technologies. Thus, there is a need for a low-cost meter and communication protocol capable of providing unidirectional communications to a remote meter reader while avoiding interference from other meters as well as other radio frequency transmissions within the communication range of the meter reading device.